Combination therapy of rat brain tumours using localized interstitial hyperthermia and intra-arterial chemotherapy

Several investigators have reported that a high concentration of drugs in a tumour can be achieved using intra-arterial (IA) chemotherapy. This treatment was highly effective, especially in brain tumours, but the actual therapeutic advantage is still unknown. There are also indications that human malignant gliomas can effectively be treated using interstitial hyperthermia. Therefore, a combined treatment of IA chemotherapy and interstitial hyperthermia should be very promising and this has been studied in a tumour model. Wistar rats with isotransplanted C 6 gliomas in the brain were treated with adriamycin (ADR, 1.0 mg/kg body weight) either infused via the carotid artery (i.a.) or via the tail vein (i.v.), with or without interstitial hyperthermia. Hyperthermia of the tumours was applied using a homemade radiofrequency antenna (RF-heating) and a heating device that maintained the tumour temperature above 40°C. Concentration of adriamycin in tumours after treatment was measured using HPLC. The effectiveness of treatment was determined by the survival time of the animals and histopathological examinations. The highest uptake of adriamycin in the rat C 6 glioma was obtained when the animals were treated with hyperthermia and i.a. ADR infusion ( p <0.01). These animals also showed significantly longer overall survival time (SF50=46 days) in comparison to the other treatments ( p < 0.05). The histological studies demonstrated a necrotic tumour; however, the surrounding normal brain tissue remained intact. Thus, a combination of IA chemotherapy with adriamycin and localized interstitial hyperthermia enhances considerably the efficacy of adriamycin and has a greater antitumour effect for malignant brain tumours. This method is suitable for clinical use, and may be a new strategy for treating gliomas not successfully treated today.     

The effect of thermotherapy using magnetic nanoparticles on rat malignant glioma

Summary Thermotherapy using magnetic nanoparticles is a new technique for interstitial hyperthermia and thermoablation based on magnetic field-induced excitation of biocompatible superparamagnetic nanoparticles. To evaluate the potential of this technique for minimally invasive treatment, we carried out a systematic analysis of its effects on experimental glioblastoma multiforme in a rat tumor model. Tumors were induced by implantation of RG-2-cells into the brains of 120 male Fisher rats. Animals were randomly allocated to 10 groups of 12 rats each, including controls. Animals received two thermotherapy treatments following a single intratumoral injection of two different magnetic fluids (dextran- or aminosilane-coated iron-oxide nanoparticles). Treatment was carried out on days four and six after tumor induction using an alternating magnetic field applicator system operating at a frequency of 100 kHz and variable field strength of 0–18 kA/m. The effectiveness of treatment was determined by the survival time of the animals and histopathological examinations of the brain and the tumor. Thermotherapy with aminosilane-coated nanoparticles led up to 4.5-fold prolongation of survival over controls, while the dextran-coated particles did not indicate any advantage. Intratumoral deposition of the aminosilane-coated particles was found to be stable, allowing for serial thermotherapy treatments without repeated injection. Histological and immunohistochemical examinations after treatment revealed large necrotic areas close to particle deposits, a decreased proliferation rate and a reactive astrogliosis adjacent to the tumor. Thus, localized interstitial thermotherapy with magnetic nanoparticles has an antitumoral effect on malignant brain tumors. This method is suitable for clinical use and may be a novel strategy for treating malignant glioma, which cannot be treated successfully today. The optimal treatment schedules and potential combinations with other therapies need to be defined in further studies.     

Combination therapy of rat brain tumours using localized interstitial hyperthermia and intra-arterial chemotherapy.

Several investigators have reported that a high concentration of drugs in a tumour can be achieved using intra-arterial (IA) chemotherapy. This treatment was highly effective, especially in brain tumours, but the actual therapeutic advantage is still unknown. There are also indications that human malignant gliomas can effectively be treated using interstitial hyperthermia. Therefore, a combined treatment of IA chemotherapy and interstitial hyperthermia should be very promising and this has been studied in a tumour model. Wistar rats with isotransplanted C(6) gliomas in the brain were treated with adriamycin (ADR, 1.0 mg/kg body weight) either infused via the carotid artery (i.a.) or via the tail vein (i.v.), with or without interstitial hyperthermia. Hyperthermia of the tumours was applied using a homemade radiofrequency antenna (RF-heating) and a heating device that maintained the tumour temperature above 40 degrees C. Concentration of adriamycin in tumours after treatment was measured using HPLC. The effectiveness of treatment was determined by the survival time of the animals and histopathological examinations. The highest uptake of adriamycin in the rat C(6) glioma was obtained when the animals were treated with hyperthermia and i.a. ADR infusion (p <0.01). These animals also showed significantly longer overall survival time (SF50 =46 days) in comparison to the other treatments (p < 0.05). The histological studies demonstrated a necroti c tumour; however, the surrounding normal brain tissue remained intact. Thus, a combination of IA chemotherapy with adriamycin and localized interstitial hyperthermia enhances considerably the efficacy of adriamycin and has a greater antitumour effect for malignant brain tumours. This method is suitable for clinical use, and may be a new strategy for treating gliomas not successfully treated today.     

黄芩甙对大鼠脑胶质瘤的抑制作用

目的 研究黄芩甙对大鼠脑胶质瘤的作用机制.方法 建立Wistar大鼠脑深部胶质瘤模型.接种C6胶质瘤细胞后7d,将大鼠随机分为对照组(0.9％氯化钠注射液30 mg·kg-1·d-1,灌胃)、小剂量组(黄芩甙50mg·kg-1 ·d-1,灌胃)、中剂量组(黄芩甙100 mg·kg-1·d-1,灌胃)和大剂量组(黄芩甙200 mg·kg-1·d-1,灌胃).分析各组大鼠治疗后脑胶质瘤的病理学、MRI影像学和电镜检查结果,采用免疫组化染色检测p53和Bcl-2的表达,分析大鼠的平均生存时间和体重变化情况.结果 与对照组比较,大剂量组大鼠处死(濒死)前的肿瘤体积为(343.62±28.98)mm3,显著缩小(P＜0.01),生存时间为(42.83±4.77)d,显著延长(P＜0.01).对照组胶质瘤细胞p53蛋白强阳性细胞百分比为(84.47±3.74)％,中度阳性细胞百分比为(47.28±2.38)％,与阴性组[(12.91±1.07)％]比较,差异均有统计学意义(均P＜0.01);大剂量组p53蛋白强阳性细胞百分比与对照组比较,差异有统计学意义(P＜0.01).对照组Bcl-2蛋白强阳性细胞百分比为(86.51±4.17)％,中度阳性细胞百分比为(48.19±2.11)％,与阴性组[(10.36±1.43)％]比较,差异均有统计学意义(均P＜0.01).电镜检查结果显示,黄芩甙可使胶质瘤细胞核和细胞器发生破坏.结论 黄芩甙对在体脑胶质瘤有明显抑制作用,其作用机制可能与下调突变型p53引发细胞凋亡有关,但与Bcl-2无关.     

Acute histological effects of interstitial hyperthermia on normal rat brain

Histological changes in the brains of Fischer rats at different times after interstitial heating with various thermal doses were studied. The brains, subjected to sham-heating, and heating at 39 and 40^oC for 30min showed mild capillary congestion and minimal vacuolation at 4, 24 and 72h. In the brains heated to 41, 42 and 43^oC for 30min, there was local vascular congestion, petechiae, vacuolation and cellular shrinkage with nuclear pyknosis at 4h; enhanced congestion and petechiae, acute cellular necrosis, infiltration of polymorphonuclear leukocytes and marked vacuolation at the margin at 24h; total coagulative necrosis of all parenchymal and vascular elements, early liquefaction necrosis and vascular hyperplasia at the margin at 72h; enhanced vascular hyperplasia at the margin at 120h and 168h. The threshold thermal dose for the histopathological damage in the rat brain was heating at 41^oC for 30min.     

Therapeutic efficacy of targeting chemotherapy using local hyperthermia and thermosensitive liposome: evaluation of drug distribution in a rat glioma model

A method was developed of targeting chemotherapy using thermosensitive liposomes to treat malignant gliomas. Using the brain heating system, when the tumour core is heated to >43°C, the tumour infiltrating zone is exposed to mild hyperthermia (40–43°C). Thermosensitive liposomes were designed to release their contents at 40°C to target both the tumour core and tumour infiltrating zone. The present study investigated the anti-tumour effect on rat glioma models in tumour drug uptake and tumour growth delay studies. Elevated accumulation of ADR in the rat C6 glioma after treatment was obtained in the area heated to >40°C. However, there was no significant difference between the areas heated to 40–42°C and >43°C. Furthermore, it was found that ADR concentrations in the mildly hyperthermic areas were significantly higher following treatment with liposomal ADR than with free ADR. The animals treated with the new combination therapy had significantly longer overall survival time in comparison to those receiving other treatments. Thus, thermosensitive liposomes release their contents in response to mild hyperthermia and this combination therapy has a greater therapeutic efficacy for malignant brain tumours. This method is a promising approach for the treatment of malignant glioma patients.     

Novel magnetic resonance imaging contrasts for monitoring response to gene therapy in rat glioma

Magnetic resonance imaging relaxation times, T(1rho) and Carr-Purcell T(2) (CP-T(2)), were measured in a glioma herpes simplex virus-thymidine kinase gene therapy model. In treated tumors with >50% cell death by histology, T(1rho) and CP-T(2) measured with short spacing (tau(CP)) between centers of adiabatic refocusing pulses showed similar enhanced sensitivity to cytotoxic cell damage over CP-T(2) measured with long tau(CP) (long-tau(CP) T(2): 54.3 +/- 0.7 and 55.4 +/- 1.2 ms, P = 0.30; short-tau(CP) T(2): 61.3 +/- 1.0 and 64.2 +/- 1.1 ms, P < 0.05 before and day 2 of treatment, respectively). Without treatment, long-tau(CP) T(2) provided the most pronounced contrast between tumor and normal cerebral tissue. These data demonstrate that endogenous T(2) contrast can be modulated and extended in a manner likely to be clinically important.     

Therapeutic efficacy of targeting chemotherapy using local hyperthermia and thermosensitive liposome: evaluation of drug distribution in a rat glioma model.

A method was developed of targeting chemotherapy using thermosensitive liposomes to treat malignant gliomas. Using the brain heating system, when the tumour core is heated to >43 degrees C, the tumour infiltrating zone is exposed to mild hyperthermia (40-43 degrees C). Thermosensitive liposomes were designed to release their contents at 40 degrees C to target both the tumour core and tumour infiltrating zone. The present study investigated the anti-tumour effect on rat glioma models in tumour drug uptake and tumour growth delay studies. Elevated accumulation of ADR in the rat C6 glioma after treatment was obtained in the area heated to >40 degrees C. However, there was no significant difference between the areas heated to 40-42 degrees C and >43 degrees C. Furthermore, it was found that ADR concentrations in the mildly hyperthermic areas were significantly higher following treatment with liposomal ADR than with free ADR. The animals treated with the new combination therapy had significantly longer overall survival time in comparison to those receiving other treatments. Thus, thermosensitive liposomes release their contents in response to mild hyperthermia and this combination therapy has a greater therapeutic efficacy for malignant brain tumours. This method is a promising approach for the treatment of malignant glioma patients.     

Acute histological effects of interstitial hyperthermia on normal rat brain.

Histological changes in the brains of Fischer rats at different times after interstitial heating with various thermal doses were studied. The brains, subjected to sham-heating, and heating at 39 and 40 degrees C for 30 min showed mild capillary congestion and minimal vacuolation at 4, 24 and 72 h. In the brains heated to 41, 42 and 43 degrees C for 30 min, there was local vascular congestion, petechiae, vacuolation and cellular shrinkage with nuclear pyknosis at 4 h; enhanced congestion and petechiae, acute cellular necrosis, infiltration of polymorphonuclear leukocytes and marked vacuolation at the margin at 24h; total coagulative necrosis of all parenchymal and vascular elements, early liquefaction necrosis and vascular hyperplasia at the margin at 72 h; enhanced vascular hyperplasia at the margin at 120 h and 168 h. The threshold thermal dose for the histopathological damage in the rat brain was heating at 41 degrees C for 30 min.     

Mitigation of eddy current heating during magnetic nanoparticle hyperthermia therapy

Background: Magnetic nanoparticle hyperthermia therapy is a promising technology for cancer treatment, involving delivering magnetic nanoparticles (MNPs) into tumours then activating them using an alternating magnetic field (AMF). The system produces not only a magnetic field, but also an electric field which penetrates normal tissue and induces eddy currents, resulting in unwanted heating of normal tissues. Magnitude of the eddy current depends, in part, on the AMF source and the size of the tissue exposed to the field. The majority of in vivo MNP hyperthermia therapy studies have been performed in small animals, which, due to the spatial distribution of the AMF relative to the size of the animals, do not reveal the potential toxicity of eddy current heating in larger tissues. This has posed a non-trivial challenge for researchers attempting to scale up to clinically relevant volumes of tissue. There is a relative dearth of studies focused on decreasing the maximum temperature resulting from eddy current heating to increase therapeutic ratio.

Methods: This paper presents two simple, clinically applicable techniques for decreasing maximum temperature induced by eddy currents. Computational and experimental results are presented to understand the underlying physics of eddy currents induced in conducting, biological tissues and leverage these insights to mitigate eddy current heating during MNP hyperthermia therapy.

Results: Phantom studies show that the displacement and motion techniques reduce maximum temperature due to eddy currents by 74% and 19% in simulation, and by 77% and 33% experimentally.

Conclusion: Further study is required to optimise these methods for particular scenarios; however, these results suggest larger volumes of tissue could be treated, and/or higher field strengths and frequencies could be used to attain increased MNP heating when these eddy current mitigation techniques are employed.     

冷冻联合rhTNF-α治疗C6大鼠脑胶质瘤的实验研究

目的探讨冷冻联合rhTNF-α治疗C6大鼠脑胶质瘤的可行性。方法借助于立体定位技术,将C6胶质瘤细胞接种于40只雄性Wister大鼠脑S1区,待肿瘤长至第15天,直径约6mm时,随机将荷瘤鼠分为四组:G1、G2、G3、G4分别为盐水对照组、冷冻治疗组、rhTNF-α治疗组及联合治疗组,每组10只,同时分别行相应的治疗。治疗后第15天,行核磁共振(MRI)检查,测量肿瘤体积和抑瘤率。动态观察各组荷瘤鼠生存期和rhTNF-α对荷瘤鼠的毒副作用。结果联合治疗组肿瘤体积和生存期与其它各组相比差异有显著性,且该组对肿瘤生长的抑制率(89.5%)明显大于冷冻组(66.3%)和rhTNF-α治疗组(49.0%),且大于理论抑瘤率(82.8%)。同时观察到rhT-NF-α对实验动物有一定毒副作用。结论冷冻和rhTNF-α联合应用,具有协同抗肿瘤作用,为进一步临床研究提供了实验依据。     

The safety and efficacy of olaparib therapy in patients with relapsed ovarian cancer

Introduction: PARP inhibition is an exciting new anticancer strategy. Olaparib has recently obtained a first in class license in Europe and the USA for the treatment of relapsed BRCA-mutant ovarian cancer.

Areas covered: We review the key preclinical and clinical data surrounding its use in the maintenance setting.

Expert commentary: We also consider the market profile, regulatory issues surrounding the agent and offer a five year speculative viewpoint of its future development in ovarian cancer.     

Interaction between microwave-induced brain hyperthermia and high dose rate radiation in the BT4An brain glioma in rats

Summary The cerebral BT₄An glioma model in BD IX rats was used to study the effect of hyperthermia given in combination with radiotherapy (thermoradiotherapy) in the treatment of brain tumours. A single treatment with high dose rate radiation was given to a local brain field. Local brain hyperthermia was given at 42.4° C for 45 min by externally applied microwaves (700 MHz), immediately before radiotherapy (10 Gy).In a pilot study, thermoradiotherapy increased the median life span with 20 days compared to controls, which was significantly better than that observed after radiotherapy alone (7 days). In an extended experiment the corresponding figures for thermoradiotherapy, hyperthermia alone and radiotherapy alone were 12.5, 3.5, and 3.5 days, respectively. Thermoradiotherapy was significantly better than radiotherapy and hyperthermia alone. There was no acute mortality in these experiments. Neurological side-effects were infrequent, of slight degree and reversible. The present study shows that a survival benefit of adding hyperthermia to radiotherapy can be achieved without unacceptable neurological side-effects in an animal glioma model.Presented in part at the meeting of the European Society for Hyperthermic Oncology (ESHO), Brussels, June 17, 1993     

Early effects of boron neutron capture therapy on rat glioma models

Early effects of boron neutron capture therapy (BNCT) on malignant glioma are characterized by reduction of the enhancement area and regression of the peritumoral edema radiologically. The aim of this study was to investigate the early histological changes of tumors and inflammatory cells after BNCT in the rat brain. Rats were treated with BNCT using boronophenylalanine (BPA) 7 days after implantation of C6 glioma cells. The tumors were assessed with magnetic resonance imaging and histopathological examination at 4 days after BNCT. The mean tumor volumes were 39 ± 2 mm³ in the BNCT group and 134 ± 18 mm³ in the control group. In the BNCT group, tumor cells showed a less pleomorphic appearance with atypical nuclei and mitotic figures. The Ki-67 labeling index was 6.5% ± 4.7% in the BNCT and 35% ± 3.8% in the control group. The reactions of the inflammatory cells were examined with ED-1 as macrophage marker and OX42 as microglia marker. ED-1- and OX-42-positive cells were reduced both in the core and the marginal area of the tumor in the BNCT group. It is suggested that BNCT reduced tumor progression by suppression of proliferation. Inhibition of the activated macrophages may relate to reduced peritumoral edema in the early phase.     

热疗在胶质瘤治疗中的研究进展

胶质瘤是很常见的恶性脑肿瘤,目前主要治疗方法包括手术、放疗与化疗,但患者生存率较低、预后较差。上述方法的一些局限性促使人们寻找更有效、更安全的治疗方法。热疗是一种局部或全身加热,利用高温杀灭肿瘤细胞,从而达到治疗效果的方法。在胶质瘤治疗中有着如创伤性小、精确性高等优点,与放化疗联用可以改善预后。目前已作为一种具有极大潜在优势的胶质瘤治疗手段。本文主要介绍应用于胶质瘤治疗的热疗方法,热疗在胶质瘤治疗中的应用前景与应用现状,以及研究相对成熟且已上市的、可应用于胶质瘤热疗的设备及操作方法。     

超选择性颅内动脉灌注贝伐珠单抗治疗复发恶性脑胶质瘤的疗效及安全性

目的:观察超选择性颅内动脉灌注贝伐珠单抗治疗复发恶性脑胶质瘤的疗效及安全性。方法:纳入2017年10月至2020年11月在我院神经外科接受超选择性颅内动脉灌注贝伐珠单抗治疗的11例复发恶性脑胶质瘤患者,观察治疗后的无进展生存期、Karnofsky评分及不良反应,随访终点为肿瘤再次出现复发或转移。结果:经2个周期治疗后,11例复发恶性脑胶质瘤患者的疾病控制和客观反应人数分别为10例和8例,患者Karnofsky评分较治疗前显著提高(P<0.05)。中位无进展生存时间为6个月,11例患者中有1例出现皮肤过敏,1例患者出现白细胞减少。结论:采用超选择性颅内动脉灌注贝伐珠单抗治疗复发恶性脑胶质瘤安全、有效,值得临床进一步推广应用。     

Interaction between rat glioma cells and normal rat brain tissue in organ culture

A system for coculture between normal rat brain fragments and multicellular spheroids of rat glioma cells is described. The tumor cells were derived from fetal BD IX rats treated transplacentally with the carcinogen N-ethyl-N-nitrosourea (CAS: 759-73-9). Brain fragments were obtained from fetal BD IX rats and precultured for 20 days before confrontation with multicellular tumor spheroids. The cocultures were grown in nonadherent stationary organ culture for 30 days. Due to morphologic similarities between normal brain cells and tumor cells, the tumor cells were labeled with tritiated thymidine, which made them easily recognizable in autoradiographs. The two structures adhered to each other, and glioma cells progressively invaded and replaced the normal brain tissue. Invasion and replacement are characteristic features of brain tumors in vivo. Therefore, this organotypic and syngeneic model may be useful for investigation of these phenomena outside the body.     

Transmission electron microscopy of cocultures between normal rat brain tissue and rat glioma cells

An ultrastructural study of cocultures between fragments of normal rat brain tissue and aggregates of BT 5C rat glioma cells is herein described. Glioma cells invaded and replaced the peripheral parts of the brain fragments. Degeneration of brain tissue was seen all over the normal structures. Specialized junctional structures between normal and malignant cells were observed. The phagocytic activity of invading glioma cells was not increased as compared to non-invading cells. Insofar as interaction between normal brain tissue and glioma cells can be studied in detail in these cocultures, they may also be useful as a test system for the study of potential chemotherapeutic agents against gliomas.     

Antiepileptics in brain metastases: safety,efficacy and impact on life expectancy

The aim of the study was to evaluate efficacy, safety and impact on life expectancy of levetiracetam (LEV), oxcarbazepine (OXC) and topiramate (TPM) monotherapy in patients with seizures related to brain metastases. We conducted a prospective observational study on 70 patients with brain metastases. Thirteen patients were excluded because they were in prophylactic therapy with antiepileptics, nine patients did not return to our Center. A total of 48 patients with epilepsy related to brain metastases were enrolled. Patients were treated with LEV, OXC and TPM in monotherapy and followed until their death. Eighteen patients dropped out. Therefore, we followed 30 patients. Mean duration of follow-up was 6.1 months. Upon visiting the patients prior to their death (i.e. last visit preceding the death of the patients), we observed a significant reduction (P < 0.001) in the mean monthly seizure frequency; with 19 patients (63.3%) obtaining complete seizure control in the whole population. A significant improvement of seizure frequency was also observed considering each antiepileptic treatment group separately. Median survival time was similar among the three groups of patients and was similar to Class I of prognostic factors of Radiation Therapy Oncology Group. Logistic regression showed that systemic treatments did not influence the antiepileptics’ efficacy on seizure control (P = 0.614). In conclusion, regarding the use of newer antiepileptics in patients with seizures related to brain metastases, our data indicate that LEV, OXC and TPM significantly reduce seizure frequency (independently of systemic treatment), produce few side effects and appear not to affect life expectancy.